`logging.shutdown()` should clear `logging._handlerList` if that's what it's called with

Bug report

Bug description:

In the wild, I've encountered situations where logging.shutdown gets called more than once in a process.

The current implementation is called with logging._handlerList by default, meaning that handlers can have their flush() and close() methods called more than once, which can cause bad things to happen if those handlers are not amenable to being closed more than once.

If logging.shutdown() is processing logging._handlerList, it should clear that list once it finished to prevent handlers having their flush() and close() methods called more than once.

CPython versions tested on:

3.12, CPython main branch

Operating systems tested on:

Linux, macOS

Linked PRs

• gh-129681

Inizia dal punto di ingresso logging.shutdown() ed esamina come elabora logging._handlerList, incluse le chiamate ripetute a flush() e close() descritte nel report. Conferma che shutdown svuoti l’elenco predefinito degli handler dopo averlo elaborato e verifica che chiamate ripetute a shutdown non elaborino nuovamente gli stessi handler.